Looking for T5 advice

[fastlane65]

The T5 in my '67 coupe has never shifted well under power. It was a brand new world class unit when I put it in the car four years ago. It probably had about 3000 miles on it, mostly casual driving. Filled it with Mobile1 synthetic ATF and put a Pro5.0 shifter on it. King Cobra clutch behind a 345 HP GT40 crate motor.

Last night I took the car to the local dragstrip for the first time. I could not shift under power. Car would not go into gear until I let off and got the RPMs way down. A two second 1 to 2 shift really kills your 1/4 mile times.

Any thoughts, suggestions, advice?

Thanks.

 

[F8LSNAKE]

Are you sure it's not low on fluid? I had this problem once with my tko and that's all it turned out to be. Everyone kept telling me you couldn't powershift them over 6000. After I topped it off it shifted fine under load at higher rpms. All the t-5s I have owned shifted great until the dissentegrated. They aren't real strong, but will hold up decent in a light car(under 3000lbs).

 

[red9450]

I second the low fluid. mine did the same.